Primary Sampling System

It is very likely that the re-combined, primary sample taken from the whole is going to be too large for most powder tests and it, therefore, needs to be sub-divided into secondary or even tertiary sub-samples. This sub-division may be built into the primary sampling system or it may be achieved with a separate sample divider. Allen1 reviewed and tested most methods available for sample splitting and found the one based on the spinning riffler to be the best. 

As was mentioned earlier, the primary sampling system can be operated either in intervals of constant time or constant mass. The constant mass option makes the design and operation of the secondary, subdivision system simpler. It requires a continuous weighing system, like a belt scale, installed near the primary cutter, preferably before it. This monitors the mass flux of the solids conveyed and adjusts the speed of the primary cutter before each cut this generates a primary increment of constant mass, thus preventing collection of excessive amounts which would overload the secondary system and yet always more than the minimum amount specified for the top size if the handling rate is low. 

The reactor coolant system interfaces with a number of auxiliary systems, principally the ehemical and volume control system, the normal residual heat removal system, the steam generators, the primary sampling system, the liquid radwaste system and the eomponent cooling water system. 

The sample heat exchanger in the primary sampling system. 

Borated reactor-grade waste water collected from the reactor coolant system effluents received through the chemical and volume control system, the primary sampling system sink drains and equipment leak offs and drains. 

The primary sampling system is a manually operated system. It eolleets representative samples of fluids Ifom the reactor coolant system and various primary auxiliary system process streams for analysis by the plant operating staff. This sampling process is performed during normal plant operations. 

The following requirements for the primary sampling system support safe operation of the plant tmder normal conditions ... 

The primary sampling system must maintain the integrity of the primary coolant botmdary. 

The primary sampling system must be able to provide a representative sample of the primary coolant, whilst minimising operator doses to levels that are ALARP. 

The primary sampling system collects representative samples of primary coolant..During normal operation, the primary sampling system collects representative samples of fluids in the following reactor coolant system and auxiliary primary systems process streams ... 

Further information about operation of the primary sampling system is provided in Section 9.3.3 of Reference 6.1. 

Doses to the operator associated with the use of the primary sampling system ate ALARP. A delay coil of tubing is installed inside containment to provide at least 60 seconds of transit time for the sampling fluid to exit the containment from the hot leg. This 60-second delay is needed for N-16 decay. Control and instrumentation is provided for safe, reliable operation. Sample flow is routed to a grab sampling unit. This unit is in an enclosure, which controls the spread of contamination... 

Primary sampling system liquid sample radiation monitor. The monitor s primary function is to indicate elevated reactor coolant sample radiation levels following a design basis event or severe accident. It may also be used to provide early indication of a possible fuel cladding breach. The monitor isolates the sample flow and initiates an alarm in the main control room and locally. 

Primary sampling system gaseous sample radiation monitor. The monitor provides indication of significant radioactivity in a gaseous sample taken from the containment atmosphere. The monitor initiates an alarm locally and in the main control room. 

Primary sampling system liquid sample radiation monitor ... 

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